Has anyone actually used the auto start/stop feature? To me is seems like a weak attempt by BMW to make an environmental statement. The M3 is awful on gas (who cares with such performance), I'm sure that turning it off at traffic lights once in a while won't make a difference.

Tried it once just to make sure it worked. I personally feel like thats a little too hard on the engine to keep turning it off and starting it back up. Even with that, I would never think of using it. Stupid feature.

Actually, I use it for selected trips and driving situations. Call me wimpy, but there's nothing wrong to me with saving some fuel and reducing emissions, albeit only a bit.

According to BMW:

"According to the standardised consumption test specified by legislation and conducted on the chassis dynamometer, there is a 3% saving in fuel. In everyday driving situations the savings potential can be as high as 1.5 litres (continuous running), depending on the route profile. The greatest savings effect is of course obtained in congestion and urban traffic."

And it works just fine, I just anticipate re-starting by 1-2 seconds, lessen the pressure on the brake pedal (not even removing it), and the engine fires up, ready to go. The only issue I have is that my V1 reboots with every engine restart, but I don't really need the V1 in urban traffic congestion anyways so I turn it off.

Sure, I use a lot of gas with my M3. And yes, I know, I can afford this car, so I can afford the barrels of gas that I burn as well. But why not save 3%?

Exactly, if it's possible and doable then why not? The M3's engine may be thirsty, but one would be a fool to think BMW paid NO attention to fuel efficiency at all in designing it. So what's wrong with their adding just one more aspect to further increase the fuel economy by a little bit?

No, this is a waste of gas and wear on engine. Did this once while I was stuck in traffic, must have started and stopped at least 75 times in 2 hrs. That's like 1/3 years worth of driving. I'll never use it again

i agree, but also should note that hot restarts are nothing for engines - its actually ice cold starts that do the most wear on the engine, like 90%, unless you're doing something extreme with the motor

You can because it's by default off. What you can't do is leave it on.

Quote:

Originally Posted by kyoo

i agree, but also should note that hot restarts are nothing for engines - its actually ice cold starts that do the most wear on the engine, like 90%, unless you're doing something extreme with the motor

Not only that, these start-stop mechanicals are beefed up and the engine is stopped in a specific way to make restarts even easier on it and quicker than usual.

I use this feature when I'm in LA almost constantly, knowing you're not wasting priceless fuel when stopped at the light does give some relief. I've learned a trick to make this feature a little more fitting to my preferences (this is applicable to m3's equipped with dct). For example, when you come up to a red light and you know it's going to turn green any second, or it's a situation where you may need to keep inching forward (stop sign), I fully stop the car and then release the brake. This keeps it from turning off, but obviously the surface has to be flat and the brake should be covered. It takes approximate 1.5 seconds for it to turn off with the brake fully applied and the car stopped. I wouldn't recommend using this feature on freeway traffic unless your not moving at all for extended periods (I don't usually make the motor turn off unless I anticipate sitting for 10+ seconds).

I disagree that this will cause wear on the motor, if it is it's negligible and the motor idling causes just as much or more. The wear item from this feature is the starter, and BMW has equipped cars with this feature with heavy-duty starters to compensate for it.

As far as the time it takes to start back up and go, it's really nothing. You don't have to let the RPMs settle after the restart, you just give it gas after the I initial start and the clutch enacts and your off.